Ice dam risk in Lebanon, PA
How often ice dams form in Lebanon
6.7 dam days a winter
Moderate risk. On an ordinary house in Lebanon, conditions for an ice dam come on about 6.7 days in a normal winter, mostly in January and February.
Lebanon averages 24 inches of snow a year and about 26 days with snow on the ground. Most of it comes and goes within a few days. The conditions that make a dam need all three at once: snow, cold at the eave and heat above it.
What your attic does to that number in Lebanon
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 4.4 | Low |
| Typical, some insulation, not air-sealed | 6.7 | Moderate |
| Older or poorly insulated, warm attic | 9.6 | Moderate |
Sealing and insulating a typical attic takes out about 2.3 days a winter here. It drops the risk from moderate to low.
What to do about ice dams in Lebanon
- Air-seal the attic floor: the gaps around the hatch, light fixtures, plumbing stacks and the top plates of interior walls. This is the fix that removes the cause, and it usually costs less than a season of contractor ice removal.
- Rake the bottom three or four feet of roof after any storm that leaves more than about six inches, from the ground with a roof rake.
Which to spend on first: air sealing or heat cable.
Lebanon winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 6.8 | 9.4 | 2.8 |
| February | 7.8 | 8.8 | 2.4 |
| March | 4.2 | 2.8 | 0.5 |
| April | 0.4 | 0.2 | 0.0 |
| October | 0.3 | 0.1 | 0.0 |
| November | 0.5 | 0.3 | 0.0 |
| December | 4.0 | 4.2 | 1.0 |
Lebanon next to nearby towns
Lebanon ranks 54 of 68 Pennsylvania cities here for ice-dam days, behind St. Marys at 26.9 days.
- Elizabethtown, PA 16 mi, 6.5 days
- Ephrata, PA 17 mi, 6.4 days
- Columbia, PA 22 mi, 6.5 days
- Lancaster, PA 22 mi, 5.3 days
- Wyomissing, PA 24 mi, 7.6 days
Where these numbers come from
NOAA 1991–2020 climate normals from Lebanon 2 W, 2.1 miles from Lebanon. A dam day is a day with snow on the roof and freezing at the eave while heat or sun melts the snow above it. This describes a normal winter, not this one.